I am very new to lucid dreaming, but the two times I have had a lucid dream, I had them because of a trigger I set. My trigger is usually a visual. I guess it's similar to the idea of dreamsigns, but not quite the same.

The trigger I use the most is my hands. During the waking hours, whenever I see my hands, I remember to do a reality check. So whenever I'm in dreams if I see my hands, I become aware in the dream. Hope that's helpful to someone...